This disclosure relates generally to a connection shaft for a motor-generator and, more particularly, to venting the motor-generator through the connection shaft.
Turbomachines, such as gas turbine engines, are known. Typical turbomachines include a compression section having large rotors. During startup, the rotors must be accelerated to high rotational speeds until the rotors rotate fast enough to sustain operation of the turbomachine. A motor-generator may be used to accelerate the rotors. The motor-generator is rotatably coupled to the turbomachine through a connection shaft. Once the turbomachine is self-sustaining, the turbomachine rotatably drives the motor-generator, which generates power that is supplied to various components.
It is sometimes desirable to decouple the turbomachine from the motor-generator to ensure that errors or failure modes are not communicated between the turbomachine and the motor-generator. Accordingly, the connection shaft is movable to a position that is decoupled from the motor-generator. In the decoupled position, the connection shaft rotates relative to the motor-generator. As known, pressures inside the motor-generator can exert undesirable loads on the connection shaft when the connection shaft is disconnected from the motor-generator. The loads, and thermal energy levels resulting from the loads, can damage and degrade various components, such as the bearings that support the connection shaft or seals near the connection shaft.